Pörtner, Hans-Otto
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Pörtner, Hans-Otto
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Pörtner, Hans-Otto
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Pörtner, H.-O.
Pörtner, Hans-O.
Pörtner, Hans Otto
Poertner, Hans-Otto
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hans.poertner@awi.de
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12 Ergebnisse
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Item-typ:Veröffentlichung, Modelling temperature effects on population-specific growth patterns of Atlantic cod (Gadus morhua)(2022-11-01); ; ; Human-induced climate change has been affecting oceans' temperatures for several decades (IPCC, 2014). Temperature is one of the most important environmental factors influencing metabolic rates and therefore development, growth and reproduction of terrestrial and marine organisms (Clarke, 2017). Growth rates of ectotherms (e.g. fish species) are expected to be altered by climate-induced temporal and spatial changes in ocean temperatures (Pörtner, 2010; Pörtner et al., 2014). Studies suggest that warming will have differential effects on fish body size with the major trend of reduction in mean species size across latitudes (Forster et al., 2012; Cheung et al., 2013; Audzijonyte et al., 2020). The thesis aims to bridge advanced knowledge and methodology of various kinds of research, such as climate physics and climate modelling, theoretical, experimental and observational biology, and biophysical modelling in order to investigate temperature effects on fish growth from both historical and future climate perspectives. In particular, the study is dedicated to the main subject - the role of different thermal environments in shaping the growth patterns of Atlantic cod (Gadus morhua) with the focus on the Northeast Atlantic populations. Additionally, the author addresses methodological aspects, advantages and limitations of a modelling study in a context of eco-physiological research and introduces an open source modelling tool that can help link findings from experimental (physiology) and observational (ecology) studies.Dissertation285 123 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Energy budget, growth and exercise as proxies for performance capacity and fitness in Arctic fishesThe boreal Atlantic cod (Gadus morhua) is entering the Arctic in response to rising water temperatures, likely increasing predation pressure on the endemic key species Polar cod (Boreogadus saida). In this thesis, I investigated the whole-animal performance of both fish species after long-term acclimation to future ocean acidification and warming conditions in order to estimate their future competitive strength. More precisely, I focused on aerobic performance such as baseline and maximum metabolism, as well as energetic investment into growth and swimming as indicators for fitness capacity under future ocean conditions. While G. morhua was thriving under conditions projected for the year 2100, the competitive strength of B. saida likely decreases. F.i., the growth performance of B. saida decreased at temperatures above 6 degree Celsius and the swimming performance was impaired under elevated PCO2 levels, potentially resulting in a higher vulnerability to predation and reduced foraging success.Dissertation399 155 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Oysters under anthropogenic pressure: A cellular perspective on the interactive effects of microplastic pollution and climate change(2025-09-24); 18 352 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Wirkungen von CO2 auf die Temperaturtoleranz und Fitnessindikatoren einer Crustaceenart aus verschiedenen Klimazonen(2010-11-08); ; ; Anthropogenic CO2 emissions threaten marine ecosystems by increasing water temperature and ocean acidification. In this study the impacts of climate change on the thermal tholerance of the spider crab Hyas araneus (L.) were investigated. Population comparisons were conducted on populations from Svalbard (79°N, habitat temperature 0 - 6 °C) and Helgoland (54°N, habitat temperature 3 - 18 °C), representing the species s northern and southern distribution range which is the temperate Northeast Atlantic to the Sub-Arctic region. The thermal tolerance window of H. araneus from Helgoland (54°N) was determined by measurements of the heart rate and hemolymph oxygen partial pressure upon temperatures ranging from 0 to 25 °C. Elevated CO2-concentrations induced a lowering of upper critical temperature from beyond 25 °C down to 23.5 °C (710 ppm). An increase of environmental CO2 concentrations to 3000 ppm caused a concomitant drop of the upper critical temperature to 21.1 °C. These results indicate, that the H. araneus population from Helgoland will knock on its physiological borders by synergistic effects of warming (up to 22.5 °C) and elevated CO2 concentrations. Additionally, studies on the impacts of climate change on early, potentially more sensitive life stages were conducted. Larvae of H. araneus of both populations were exposed to different temperatures and CO2 concentrations, revealing a temperature-dependent development. Larvae of Helgoland grew faster and had a higher fitness compared to those from Svalbard. Elevated CO2 concentration caused a disturbed development in all stages of both populations. Helgoland megalopae displayed the highest sensitivity against enhanced CO2 concentrations. In contrast, megalopae from Svalbard were more sensitive to warming. The negative effects of both, CO2 and temperature lead to the conclusion that the megalopae is a putative bottleneck stage during the species development. Moreover, the effect of climate change was investigated on the calcification capacity of the H. araneus larval stages. Elevated CO2 concentrations entailed population and temperature dependent reductions of the calcium contents of the larvae. In Helgoland larvae, reduction of calcium contents correlated positively with their body weight. In contrast, Svalbard larvae revealed a dramatic drop in calcium contents, with body weight remaining constant at cold temperatures (3 °C). Different to the Helgoland larvae, Svalbard larvae displayed increased calcification rates at warm temperatures (15 °C) under 3000 ppm CO2 exposure. Studies on Na /K -ATPase activity and expression identified additional differences in both H. araneus populations regarding thermal adaptation. Compared to Helgoland crabs, gill in vitro Na /K -ATPase activity of the Svalbard population showed a strong increment upon warming beyond their specific habitat temperature. This indicates a high thermal sensitivity of the Na /K -ATPase and a narrowed thermal window of the Svalbard population compared to the Helgoland population. Studying the effect of elevated CO2 concentrations on the thermal tolerance and fitness indicators of the spider crab Hyas araneus revealed different population specific physiological adaptations to their respective habitat temperatures. The synergistic effects of warming and ocean acidification will have negative effects on different processes of each population, related to various life stages due to physiological constraints. Furthermore, the progressing climate change will presumably lead to a nothward shift of the southern (Helgoland) distribution range of the species.Dissertation338 168 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Thermal Plasticity and Performance Adaptations in Gadid Muscle: Consequences for Activity and Lifestyle(2008-01-18); ; ; A recently developed model of thermal tolerance proposed that a hierarchy of biological functioning exists, each level of which displays different thermal tolerances. As the hierarchy is ascended from a molecular and biochemical level, through cellular, organ, systemic, whole animal and ultimately ecological levels, the windows of thermal tolerance narrow. The current study looked at the thermal plasticity and adaptational mechanisms at selected biological levels of cod populations from the North East Arctic (NEAC), the North Sea (NSC) and Newfoundland (NFC), to explore their potential impacts on activity and lifestyle.Mitochondrial proliferation and increased myoglobin expression, in combination with the reduced kick and glide duration and a lower swimming efficiency all point to a metabolic shift from anaerobic pathways at 10 degrees C, towards a greater dependence on aerobic metabolism at 4 degrees C. All Atlantic cod populations were able to maintain cellular and biochemical, physiological and systemic functioning between 4 degrees C and 10 degrees C. Although biochemical, physiological and whole animal performance were reduced at 4 degrees C, acclimation temperature had no effect. The thermal flexibility of the examined functions at the different levels of organisation observed in the current study between 4 degrees C and 10 degrees C is evidently a requirement of living in the thermally unstable environment in which Atlantic cod find themselves.Dissertation309 119 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Life in cold oceans: activity dependent on extracellular ion regulation?(2010-11-05); ; ; It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.Dissertation503 182 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Cellular metabolism of different life stages of marine teleosts during Ocean Acidification and Warming(2021-05-27); ; ; The anthropogenic emissions of greenhouse gases are causing an increase in atmospheric and oceanic temperatures. In the oceans, seawater temperature rises in parallel to the decrease in pH caused by the reaction of rising atmospheric CO2 with water. The combined phenomenon is known as Ocean Acidification and Warming (OAW). Rising temperatures and decreased water pH may induce adjustments in the energy budget of fish, requiring more energy for protein turnover and for ion and acid-base balance. Since most of these processes depend on the mitochondrial provision of ATP, this PhD project investigated if rising temperature and PCO2 affect the mitochondrial functioning with consequences for the energy budget and acclimation potential of the animals to climate changes. Mitochondria are specialised cellular organelles and their degree of specialisation may vary according to species and life-stage. To cover a broad range of this variability, this thesis analysed firstly the mitochondria of juvenile polar cod (Boreogadus saida) as polar fish and of juvenile Atlantic cod (Gadus morhua) from the Northeast Arctic population (NEAC) as temperate fish, which presently co- occur in the waters around Svalbard. Secondly, the mitochondria of juvenile NEAC were compared with the mitochondria of embryos of the same species (Øresund population) to assess the differences between life-stages. Lastly, mitochondria of Atlantic cod embryos were analysed together with the ones of Atlantic herring embryos (Clupea harengus) because of the different spawning behaviour of the two species (pelagic for Atlantic cod, benthic for herring). Polar cod and NEAC were acclimated for four months at combinations of temperature (polar cod: 0, 3, 6, 8°C; NEAC: 3, 8, 12, 16°C) and PCO2 (400 and 1170 μatm) at the end of which their cardiac mitochondrial respiration was tested. In addition, the lipid class composition in pooled cellular membranes and the capacity of a number of mitochondrial enzymes were analysed. Embryos of Atlantic cod and herring were incubated from fertilization to hatch at present and projected temperatures (Atlantic cod: 0, 3, 6, 9, 12°C; herring: 6, 10, 14°C) and PCO2 (400 and 1100 μatm). When the embryos reached the "50% eye pigmentation" developmental stage, whole-body mitochondrial functioning was assessed. Moreover, the hatching success, length at hatch and larval malformation rates were recorded. The mitochondrial parameters measured in all species were OXPHOS, proton leak, citrate synthase (CS) capacity and the capacity of the single components of the Electron Transport System (ETS) i.e., Complex I (CI), Complex II (CII) and Complex IV (CCO). Juvenile polar cod presented some stenothermal traits like the lack of adjustments of the membrane lipids, stable values of OXPHOS and ETS despite increasing temperatures and low values of CCO/ETS. The relation between OXPHOS and proton leak suggested an optimum temperature for ATP production in the 3-6°C range, while the proton leak increased dramatically at 8°C, which was not paired by OXPHOS, hence decreasing the ATP production and therefore the available energy in the cardiac cells. Since the heart plays a fundamental role in acclimation to temperature, the lower energy yield may be related to the higher mortality occurring at this temperature. Yet, polar cod mitochondria were not affected by elevated PCO2 besides the increase in CS activity, probably as compensatory response to overcome its inhibition. NEAC, on the other hand, displayed more eurythermal features like modifying the lipid components of the cellular membranes, high CCO/ETS and increasing OXPHOS and ETS with rising temperatures. Although proton leak also increased with temperature, the stable ATP production efficiency indicates the ability to control proton leak and ensure the required energy to the cellular processes in a broader range of temperatures. However, the cardiac mitochondria of NEAC were negatively impacted by incubation under elevated PCO2, especially in combination with the highest tested temperature (16°C). Individuals from that group presented lower OXPHOS, lower ETS and lower capacity of the ETS enzymes CI and CCO whereas the TCA cycle-related enzymes CS and CII were stimulated. Possibly, elevated PCO2 inhibited CS and CII which were up-regulated in order to compensate for the lower activity. If the compensation was just partial, the decrease in activity of the TCA cycle may have led to a decrease of the ETS activity and therefore of the OXPHOS capacity with negative consequences on the energy yield of the heart cells. In contrast to their juvenile conspecifics, Atlantic cod embryos possessed mitochondria with a narrower thermal window which were not sensitive to elevated PCO2. In fact, OXPHOS, ETS and CI increased with temperature until 9°C, where they reached a plateau, and CII presented the same capacity at control and high levels of CO2. However, the combination of high temperature (12°C) and elevated PCO2 exerted a negative effect at higher organizational levels, decreasing hatching success and hatchlings' length. Moreover, elevated PCO2 increased the larval malformation rates at all incubation temperatures. Similar trends were found in the embryonic mitochondria of Atlantic herring. In this species OXPHOS and CI increased with temperature until 10°C and then reached a plateau, while elevated PCO2 did not affect the mitochondrial functioning. While elevated PCO2, especially in combination with high temperatures, decreased the survival of Atlantic cod embryos, herring hatching success and hatchlings' size was only related to temperature, suggesting higher CO2-tolerance in this benthic spawner. In conclusion, with regard to the mitochondrial functioning, NEAC appeared more eurytherm and plastic in the range of temperatures projected for the waters around Svalbard at the end of the century. Despite their higher CO2- sensitivity they may outperform polar cod, displacing them or forcing them to retreat in the fjord bottom waters. The plasticity of juvenile NEAC was lowest at the embryonic level, where the thermal window was narrower and more susceptible to elevated PCO2, suggesting that embryos may be a bottle-neck for the population acclimation process. Moreover, tolerance to high CO2 may be related to the spawning behaviour, with benthic species being more tolerant than pelagic ones.Dissertation387 216 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Intra-specific variation of ocean acidification effects in marine mussels and oysters: integrative physiological studies on tissue and organism responses(2019-12-20); ; ; Ocean acidification (OA), caused by the oceanic uptake of anthropogenic CO2, is predicted to negatively affect marine mussels and oysters. In addition, the rapid rate at which OA occurs may outpace species’ ability to genetically adapt, leaving pre-existing genetic variation as a potential key to species resilience under OA. Against this backdrop, this thesis investigated the physiological mechanisms underlying intra-specific variation of OA sensitivity of Kiel Fjord blue mussels (Mytilus edulis) and Sydney rock oysters (Saccostrea glomerata). A long-term CO2 acclimation experiment with different family lines of blue mussel revealed that families whose offspring successfully settled at all experimental PCO2 levels (control, intermediate and high PCO2 level) were characterised by an inherently higher metabolic capacity at the whole animal and the cellular level compared to more sensitive family lines, whose offspring failed to survive at the highest experimental PCO2. This increased metabolic scope of tolerant family lines seems to cover elevated metabolic costs at the intermediate PCO2, however; at the highest PCO2, filtration rates and gill aerobic capacity declined, indicating an unfavourable shift in energy demand and supply. A second comparative CO2 acclimation study between a wild population of Sydney rock oysters and a more CO2 tolerant aquaculture line (selected for faster growth) showed that, in contrast to wild oysters, selected oysters were able to avoid a CO2-induced drop of extracellular pH, likely facilitated by an increased capacity for systemic CO2 release due to higher and more energetically efficient filtration rates. In conclusion, the observed pre-existing intra-specific variation in both species suggests potential adaptive capacities. However, as the physiology of marine bivalves is tightly linked with their functions within ecosystems, observed negative OA effects could have far reaching consequences at an ecosystem scale.Dissertation373 202 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Identification of lifecycle bottlenecks to assess the vulnerability of fish species to climate change(2019-11-29); ; ; Untersuchung von Klimawandeleffekten auf Kabeljau und PolardorschDissertation325 427 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, The effect of acute warming on protein turnover and oxygen demand in stenothermal and eurythermal eelpouts(2024-06-25); ; ; The increase in CO2 in the atmosphere due to the burning of fossil fuels is the main cause of climate change and thus global warming. Climate change has fundamental consequences for all organisms, including marine life. Ectothermal organisms, such as fish, are particularly affected, since their body temperature is equal to their environment. Fish have adapted to diverse temperature conditions depending in different climatic regions and thus exhibit a range of temperature adaptations. Fish in polar regions, such as Antarctic fish species, are adapted to constantly cold temperatures, while fish in temperate regions are adapted to seasonal temperature fluctuations and can survive in wide temperature windows. Thermal adaptation can be investigated by acclimating fish to certain temperatures over a long period (long-term acclimation) or during acute temperature changes (acute warming). This study investigates the differences and similarities in thermal adaptions of stenothermal and eurythermal fish during acute warming events. For this comparison, the closely related eelpout species Pachycara brachycephalum from the Southern Ocean and Zoarces viviparus from the North Sea were selected as experimental animals. During these experiments, water temperature was increased from 0°C to 10°C at a rate of 2°C day-1 for P. brachycephalum. For Z. viviparus, the temperature was increased from 4°C to 22°C at a rate of 3°C day-1. Isotopically labelled phenylalanine was injected intraperitonially at several temperature levels (P. brachycephalum: 0, 2, 4, 6, 8 and 10°C; Z. viviparus: 4, 10, 13, 16, 22°C) and after 1.5- and 3-hours gill and white muscle tissues were sampled. Protein synthesis rate was determined in both tissue types and protein degradation analyzed in the muscle by measuring cathepsin D activity and via untargeted metabolic profiling using NMR (nuclear magnetic resonance). Furthermore, oxygen consumption was measured during acute warming to draw conclusions about energy requirements. In P. brachycephalum, the rate of protein synthesis in white muscle did not change with increasing temperature. In contrast, the protein synthesis rate in Z. viviparus increased up to 16°C and then decreased slightly at 22°C. Comparing the two species at a common temperature (4 and 10°C), the protein synthesis rate in P. brachycephalum was 2-3-times higher, while the activity of cathepsin D was 10 times higher in white muscle. Both the rate of protein synthesis in the gills and whole animal oxygen demand increased exponentially in both species and no differences were found between the species when compared at a common temperature. In conclusion, these data suggest that protein synthesis in P. brachycephalum is cold-compensated and is maintained at a high rate at low temperatures. The protein synthesis rate in the white muscle of Z. viviparus only reached that of P. brachycephalum near its thermal optimum. This cold adaptation may enable P. brachycephalum to survive in the world's coldest ocean. In contrast, Z. viviparus responds very quickly to temperature differences, which occur regularly in the North Sea.Dissertation168 199